3 ms·

I've thought for a long time that this explains why the NSA is recording so much encrypted data. When QCs are available they will be able to decrypt all the thi

by api 9y ago

I've thought for a long time that this explains why the NSA is recording so much encrypted data. When QCs are available they will be able to decrypt all the things. Imagine what they'll learn.

qubex 9y ago
That’s a bit conspiracy-theorist-ish but unfortunately in the present climate and given that has transpired from the Snowden leaks not at all implausible. Either they have made a breakthrough in number theory that allows factorisation over finite fields, or they have a quantum computer already, or they are banking on having one soon. In any case, storage is so cheap that it makes sense to just record the traffic (which is useful for sigint anyway) and refer back to it “if and when”. Of course, much of what we consider “public-key encrypted” traffic is actually encrypted with a symmetric cipher whose encryption is impervious to Shor’s Algorithm… it is the key-exchange process that really uses the textbook public-key encryption algorithms. So much of the traffic is technically impervious to whatever advances they have made, but of course once you have captured the key-exchange “handshake” that sets up the session and exchanges the symmetric cipher keys, you’re all set to retrieve the plaintext from the intercept. There are public-key algorithms (particularly those based on lattices) that we currently hold to be secure against attack by quantum computers. I am surprised these are not seeing more adoption amongst the “enlightened paranoid cypherpunk elite”. Here is a primer on such “post-quantum cryptography” approaches, courtesy of the good folks at Wikipedia: https://en.wikipedia.org/wiki/Post-quantum_cryptography https://en.wikipedia.org/wiki/Post-quantum_cryptography
- api 9y ago
  In the process they'd get key exchanges too and it's easy to correlate traffic. I thought it was a really straightforward obvious idea. I'd do it if I were them and had such deep pockets. QC is clearly coming. Lots of news lately.
  - qubex 9y ago
    I was agreeing with you, of course if they have intercepted all traffic they have both public-key encryption key exchange and the resulting symmetrically encrypted traffic and that they could correlate it... I’m sorry if I was a bit longwinded and pedantic in my reply, I didn’t realise I was talking to virtual Hacker News nobility (with ten times the karma I do!).
    - api 9y ago
      Hacker News nobility is a dubious title haha. Btw on post quantum crypto: the problem is that most of it has not yet had enough conventional cryptanalysis. Makes no sense to use an algorithm immune to quantum speedup if it's conventionally vulnerable.
      - qubex 9y ago
        Yeah I know, I’m no expert, but I studied applied mathematics.

by api 9y ago

I've thought for a long time that this explains why the NSA is recording so much encrypted data. When QCs are available they will be able to decrypt all the things. Imagine what they'll learn.

qubex 9y ago

That’s a bit conspiracy-theorist-ish but unfortunately in the present climate and given that has transpired from the Snowden leaks not at all implausible. Either they have made a breakthrough in number theory that allows factorisation over finite fields, or they have a quantum computer already, or they are banking on having one soon. In any case, storage is so cheap that it makes sense to just record the traffic (which is useful for sigint anyway) and refer back to it “if and when”. Of course, much of what we consider “public-key encrypted” traffic is actually encrypted with a symmetric cipher whose encryption is impervious to Shor’s Algorithm… it is the key-exchange process that really uses the textbook public-key encryption algorithms. So much of the traffic is technically impervious to whatever advances they have made, but of course once you have captured the key-exchange “handshake” that sets up the session and exchanges the symmetric cipher keys, you’re all set to retrieve the plaintext from the intercept. There are public-key algorithms (particularly those based on lattices) that we currently hold to be secure against attack by quantum computers. I am surprised these are not seeing more adoption amongst the “enlightened paranoid cypherpunk elite”. Here is a primer on such “post-quantum cryptography” approaches, courtesy of the good folks at Wikipedia: https://en.wikipedia.org/wiki/Post-quantum_cryptography https://en.wikipedia.org/wiki/Post-quantum_cryptography

api 9y ago
In the process they'd get key exchanges too and it's easy to correlate traffic. I thought it was a really straightforward obvious idea. I'd do it if I were them and had such deep pockets. QC is clearly coming. Lots of news lately.
- qubex 9y ago
  I was agreeing with you, of course if they have intercepted all traffic they have both public-key encryption key exchange and the resulting symmetrically encrypted traffic and that they could correlate it... I’m sorry if I was a bit longwinded and pedantic in my reply, I didn’t realise I was talking to virtual Hacker News nobility (with ten times the karma I do!).
  - api 9y ago
    Hacker News nobility is a dubious title haha. Btw on post quantum crypto: the problem is that most of it has not yet had enough conventional cryptanalysis. Makes no sense to use an algorithm immune to quantum speedup if it's conventionally vulnerable.
    - qubex 9y ago
      Yeah I know, I’m no expert, but I studied applied mathematics.